Process of acceleration of gelatinization of cellulose nitric esters and liquid nitric esters and the product thereof



Patented Feb. 7, 1 939 umTED STATES PATENT OFFICE James T. Power, Wilmington, Del., and Kenneth B. Brown, Tamaqna, la.,

assignors to Atlas Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application June 7, 1937,

Serial No. 146,956

8 Claims.

This invention relates to the acceleration of-the gelatinization of cellulose nitric esters and liquid nitric esters, particularly glycerlne trinitrate and mixtures of glycerine trinitrate with its freezing point depressants, such as the glycol nitric esters, polymerized glycerine nitric esters, nitric esters of chlorhydrins, etc., andto the product resulting therefrom.

The invention of the present application'aims 10 to accomplish the objects sought by the invention described in our co-pending applications, Serial No. 705,622, filed January 6, 1934, now Patent No. 2,106,188, January 25, 1938, and Serial No. 750,736, filed October 30, 1934, now Patent No.

5 2,102,187, December 14, 1937, and to accomplish these objects in a more efficient way and in such manner as to yield an improved product. This application is a continuation in part of our copending application Serial No. 724,450, filed May 7, 1934.

The principal object of this invention is to gelatim'ze cellulose nitric esters by means of liquid nitric esters with the aid of more eflicient gelatinization accelerators than any heretofore known or used, thus making a more satisfactory product and obtaining greater speed, economy, and flexibility in the production of compositions which involve this process, as for example, smokeless powder, blasting gelatins, gelatin dynamites and plastics.

In the manufacture of explosives such as blasting gelatin, gelatin dynamites, semi-gelatins, smokeless powders, etc., which contain cellulose nitrate and liquid nitric esters such as nitroit is the usual practice to gelatiniz-e the cellulose nitrate by adding it in the fibrous form, to the liquid nitric ester or mixture of two or more nitric esters, contained in a mixer provided with an 40 agitator. The mixer may or may not be provided with means for satisfactorily applying heat. The

described, their solvent action is very slow. To

hasten the solution of the cellulose nitrate heat all the cellulose nitrate fibres is very difflcult to obtain. The fibres tendto form aggregates of more or less incompletely gelatinized cellulose nitrate. The surfaces of these aggregates are covered with a. film of gelatini zed material which glycerine, glycol nitrates, dinitrochlorhydrin, etc., a

is usually provided. Complete gelatinization of prevents the penetration of liquid nitric"ester to the interior of the aggregate in sufilcient amount to effect complete gelatinization. Even with excessive periods of mixing it is diflicult to break down all of these aggregates. The result is a distribution throughout the finished explosive of .gelatinized, partly gelatinized .and ungelatinized cellulose nitrate. The sensitiveness to detonation, the velocity of detonation and the length of time the product may be stored before it becomes unsatisfactory to use, are adversely aflected.

Increasing the time of gelatinization or elevation of the temperature of the reacting materials, while of some benefit, does not overcome the trouble and either prolongation of the time of mixing or elevation of the temperature introduces additional hazards. Acetone, alcohol-ether mixtures and similar solvents of relatively low boiling point have been tried but are not desirable because of their volatility; with resultant proneness to form explosive gaseous mixtures with air, and toxic poisoning effect on the workmen.

The present invention resides in the use of small proportions of the partially etherified alkyl ethers of the anhydro products of the aliphatic, straight chain, six carbon atom, hexahydric alcohols as accelerators in the gelatinization of cellulose nitric esters with liquid nitric esters.

The anhydro products of the hexahydric alcohols referred to are the monoanhydro and dianhydro derivativesz The monoanhydro derivatives of the aliphatic, straight chain, six carbon atom, hexahydric alcohols are formed by heating'the hexahydric alcohol until one molecule of water is driven off and an inner .ether is formed. The dianhydro derivatives are formed by heating the hexahydric alcohol until two molecules of water have been eliminated. The anhydro products with which the present invention is concerned are inner ethers which have either one or two mono-oxy, 4- to G-membered carbon oxygen rings, and at least two available hydroxyl groups. The inner ethers may be defined as cyclic carbonoxygen compounds containing one cyclic oxygen per ring (known as an oxido ring) and derived from a hexahydric alcohol by intramolecular condensation. The monoanhydro derivative contains only one carbon-oxygen ring. The dianhydro compound contains two carbon-oxygen. rings, which may or may not be of the condensed type. The inner ethers of the various hexahydric alcohols may be designated by names derived from the stem of the parent alcohol by substituting for the characteristic sumx "itol" for the alcohol, the sufllx itan" for the cyclic monoanhydro derivative or inner ether which is generally designated a hexitan, and ide for the dianhydro derivative or dicyclic inner ether which is generally designated a hexide, thus: mannitol, mannitan, mannidej sorbitol, sorbitan, sorbide; dulcitol, dulcitan, dulcide, etc. Where reference is made in this specification and inthe claims appended thereto to a partial ether of an anhydro product of a hexahydric alcohol, it is to be understood that mixtures of partial ethers of two or more of the various possible anhydro products of the hexahydric alcohols are contemplated.

While the partial ethers of the anhydro products of any aliphati straight chain, sixcarbon atom, hexahydric alcohol, such as sorbitol, mannitol, dulcitol, talitol, iditol, etc., are suitable for use in the practice of this invention, the partial ethers of the anhydro products of sorbitol and mannitol are preferred due to their availability.

This invention contemplates the use of the alkyl ethers of the foregoing and above-described anhydro derivatives of the hexahydric alcohols in which the hydrogen of one or more, but not all, of the available hydroxyl groups of the anhydro derivative have been replaced by an alkyl group having not more than five carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, nbutyl, sec. butyl, isobutyl, tertiary butyl, n-amyl, secondary n-amyl, primary iso-amyl, secondary iso-amyl, tertiary amyl, etc. The monoanhydro derivatives have four available hydroxyl groups while the dianhydro derivatives have only two available hydroxyl groups.

The use of the partial ethers of the anhydro derivatives of the aliphatic, straight chain, hexahydric alcohols described above in place of the alkyl ethers of'the polyhydric alcohols and the polymerized polyhydric alcohols in the gelatinization of cellulose nitric esters with liquid nitric esters results in important technical advantages, in that the partial ethers of the anhydro derivatives of the hexahydric alcohols have an exceedingly low vapor pressure, and are at the same time excellent accelerators for gelatinization of cellulose nitric esters with liquid nitric esters.

The partial alkyl ethers of the anhydro products of the hexahydric alcohols have a much lower vapor pressure than certain ethers of the polyhydric alcohols, with the result that the same tendency toward evaporation of the accelerating agent does not exist. In addition, there is less odor and less tendency to hardening of the finished product. The partial alkyl ethers of the anhydro derivatives of the hexahydric alcohols described herein, combine the advantages of low vapor pressure with desirable high speed of gelatinization.

Our invention may be carried out in many ways. We may add the accelerator to the mixture of cellulose nitrate and liquid nitric esters in the mixing bowl, or we may add the accelerator to the liquid nitric ester prior to the introduction of the liquid nitric ester into the bowl.

Prior, during and after the gelatinization, we may add, for example in the manufacture of gelatin dynamites, other ingredients, such as oxygen carrying inorganic salts, as ammonium or sodium nitrate; a carbonaceous combustible material, such as wood pulp and sawdust; nitrohydrocarbons; sulphur; zinc oxide; sodium chloride, etc.

An example of a preferred mode of carrying the invention into practice is as follows:-

100 parts of low freezing nitroglycerine consisting of 80% nitroglycerine and 20% ethylene glycol dinitrate are weighed into the mixing bowl. 1 part of an accelerator consisting of 78.5% of monomethyl monoanhydro sorbitol (monomethyl sorbitan) and 21.5% of dimethyl monoanhydro sorbitol (dimethyl sorbitan) was added. 1.52 parts of dynamite nitrocotton were then added. The mixture was stirred at room temperature (70-80 F.) until gelatinized. It started to gelatinize in 3 minutes and was completely gelatinized in minutes. The same ingredients without the accelerator, under identical conditions, began to gelatinize in- 6 minutes and were completely gelatinized in 90 minutes.

While we have shown in the above example the use as the gelatinization accelerator of a mixture containing both monomethyl monoanhydro sorbitol and dimethyl monoanhydro sorbitol, this is illustrative only, and it is to be understood that either may be used alone as the gelatinization accelerator. It is also to be understood that other partial ethers of the anhydro derivatives of the hexahydric alcohols may be used in place of those set forth in the above example, either alone or in combination with each other, or in combination with those used in the example. As typical examples of such other compounds there may be instanced the following: monoethyl sorbitan, diethyl sorbitan, methyl ethyl sorbitan, trimethyl sorbitan; monomethyl sorbide, monoethyl sorbide, mono n-butyl sorbide; monomethyl mannitan, monoethyl mannitan, mono n-butyl mannitan, mono n-amyl mannitan, dimethyl mannitan, diethyl mannitan, methyl ethyl mannitan, triethyl mannitan; monomethyl mannide; monomethyl dulcitan, etc. The above enumeration is not to be taken as complete or as limiting the scope of the invention which is to be limited only as set forth in the appended claims.

Having described our invention, what we claim is:

1. The process of gelatinizing cellulose nitric esters with liquid explosive nitric esters which comprises bringing about the gelatinization in the presence of an accelerator comprising an alkyl ether of an anhydro derivative of an aliphatic, straight'chain, six carbon atom, hexahydric alcohol, said alkyl ether containing at least one free hydroxyl group and its alkyl groups containing not more than five carbon atoms.

2. The process of gelatinizing cellulose nitric esters with liquid explosive nitric esters which comprises bringing about the gelatinization in the presence of an accelerator comprising an alkyl ether of a monoanhydro derivative of an aliphatic, straight chain, six carbon atom, hexahydric alcohol, said alkyl ether containing at least one free hydroxyl group and its alkyl groups containing not more than five carbon atoms.

3. The process of gelatinizing cellulose nitric esters with liquid explosive nitric esters which comprises bringing about the gelatinization in the presence of an accelerator comprising. an alkyl ether of a monoanhydro derivative of sorbitol, said alkyl ether containing at least one free hydroxyl group and its alkyl groups containing not more than five carbon atoms. 7

4. The process of gelatinizing'cellulose nitric esters with liquid explosive nitric esters which comprises bringing about the gelatinization in the presence of an accelerator comprising a mix ture of monomethyl monoanhydro sorbitol and dimethyl monoanhydro sorbitol.

esters with liquid explosive nitric esters which comprises bringing about the gelatinization in the presence of an accelerator comprising an alkyl ether of a monoanhydro derivative of mannitol, said alkyl ether containing at least one free hydroxyl group and its alkyl groups containing 'not more than five carbon atoms.

6. The process of gelatinizing cellulose nitric esters with liquid explosive nitric esters which comprises bringing about the gelatinization in the presence of an accelerator comprising an alkyl ether of a dianhydro derivative of an aliphatic. straight chain, six carbon atom, hexahydric alcohol, said alkyl ether containing at least one free hydroxyl'group and its alkyl groups containing not more than five carbon atoms.

7. The process of gelatinizing cellulose nitric esters with liquid explosive nitric esters which comprises bringing about the gelatinization in the presence of an accelerator comprising an alkyl ether of a dianhydro derivative of sorbitol, said alkyl ether containing at least one free hydroxyl group and its alkyl groups containing not more than five carbon atoms.

8. An explosive composition comprising a cellulose nitric ester gelatinized with a liquid explosive nitric ester, and a gelatinization accelerator comprising an alkyl ether of an anhydro derivative of an aliphatic, straight chain, six car- 'bon atom, hexahydric alcohol, said alkyl ether 

